Inkjet printheads typically move across print media depositing ink droplets one swath at a time to form a desired image, often in a bi-directional print mode, depositing ink when traveling to the right and then on the return path when traveling to the left, for example. During a print swath, the temperature of a thermal inkjet printhead rises, resulting in larger ink droplets having a higher drop weight being emitted near the end of a swath, appearing as an optical density or color saturation change across the swath.
During the turnaround time between print swaths, the printhead is allowed to cool to preserve printhead life, so on the beginning the next swath a lower drop weight is emitted from the cooled printhead and the image appears lighter than the previous swath. This printhead temperature ramp phenomenon produces a print quality artifact known as “banding,” which is particularly noticeable in bi-directional monochromatic printing where an alternating pattern of light and dark bands appear down each edge of the printed image.